Consider preventing the emission of empty properties in the JS index

Details

Description

Currently, for methods, we emit the following empty items:

...

"since": [],

"examples": [],

"exceptions": [],

"references": []

...

In order to further reduce the size of the index, these should never be generated. The current deserializer will handle removal of these items just fine. However, we will have to update all model elements to perform a isEmpty (or equivalent) test to prevent output of that property.

Looking at closure-library, this would save us about 2MB of file size for the Index